Huawei Error 2011 (String Reversed) 🔴 Troubleshooting Guide + Real Case

⚠️ What does Huawei Error 2011 mean?

Huawei Error 2011 indicates a PV string reversed polarity fault. This occurs when the DC input from the solar panels is connected with reversed polarity (+ and – are swapped) or when the string wiring is incorrect.

Unlike Huawei Error 2001 (High String Input Voltage), which is related to excessive DC voltage, Error 2011 is caused by incorrect polarity or wiring mistakes.

The inverter detects this condition immediately and stops operation to protect its internal circuits.

⚡ System behavior when Error 2011 occurs

🔴 Inverter shutdown

The inverter does not start or stops production immediately.

📉 Zero input detection

No valid PV string input is recognized.

⚠️ Alarm message

“String Reversed” or Error 2011 is displayed on the screen/app.

🛑 Protection mode active

The MPPT input is blocked to prevent internal damage.

🧠 Causes of Error 2011 (String Reversed)

🔌 Wrong DC polarity connection

The most common cause is reversed + and – DC cables during installation.

🔄 Incorrect MC4 connection

MC4 connectors are swapped or mismatched between strings. If you’re unsure whether the connectors were assembled correctly, see our guide: Incorrect MC4 Connector Installation – Common Mistakes and Solutions.

🧩 Wrong string configuration

PV strings are connected to the wrong MPPT input channels.

🛠️ Installation or maintenance error

Often occurs after:

inverter replacement
system expansion
rewiring work

🔍 How to diagnose the problem

Step 1: Turn off the inverter

Disconnect both AC and DC switches before inspection.

Step 2: Check string polarity with a multimeter

Measure DC voltage:

Positive value → correct polarity
Negative value → reversed polarity confirmed

Step 3: Inspect MC4 connectors

Ensure:

+ is connected to +
– is connected to –

Step 4: Verify string routing

Check that each PV string is connected to the correct MPPT input.

🛠️ How to fix Huawei Error 2011

🔄 Correct DC polarity

Swap the DC cables if polarity is reversed.

🔌 Fix MC4 wiring

Reconnect connectors according to the correct string diagram.

🧭 Reassign PV strings correctly

Ensure proper MPPT mapping in multi-string systems.

🔁 Restart the inverter safely

Turn OFF DC and AC
Wait 2–5 minutes
Turn ON DC first, then AC

🧾 Real Case: Field Experience (Critical installation mistake leading to arc fault)

In practice, this error often appears as a minor “on-paper” alarm, but in real field conditions it can become one of the most dangerous and difficult issues to troubleshoot. Huawei Error 2011 (String Reversed) is not always a simple polarity warning — under certain configurations it can lead to serious DC hazards.

This real-world case represents a combination of multiple human and technical errors that escalated into a critical situation.

⚙️ How the issue started

On a ground-mounted solar installation of approximately 30 kW, DC wiring was carried out under material limitations. Instead of standard red/black DC cables for polarity identification, only black cables were available.

From the beginning, this introduced a major risk — no clear visual polarity identification.

During cable routing through corrugated conduit, polarity was mixed up, and incorrect labels for + and – were applied later.

⚠️ Cascade of human errors

Several sequential mistakes occurred:

polarity labels were applied incorrectly
the next technician connected MC4 connectors based on these incorrect markings
during string testing, only voltage presence was checked, without verifying polarity (This is a common mistake because many technicians focus only on voltage values and forget to verify polarity before connecting the string to the inverter).
the string was finally connected to the inverter as if everything was correct

At this stage, the system was already operating with reversed polarity, but the issue had not been properly identified.

🔴 Critical configuration (the real hazard)

The most dangerous part of the situation was that this incorrectly wired string was connected in parallel with another string on the same MPPT input.

This created a closed DC loop between two sources with different polarities — a condition that can become extremely unstable under load.

⚡ What happened during disconnection

When MC4 connectors were disconnected under daylight operating conditions, a strong DC electric arc occurred.

Observed consequences included:

immediate arc formation during disconnection
partial melting of MC4 connectors
thermal damage to the MPPT input stage
failure of the inverter input section

In this case, the MPPT input of the inverter was permanently damaged due to the arc event.

🧠 Key lesson from the case

In configurations where two strings are connected in parallel on the same MPPT input:

Any work on strings with uncertain or incorrect polarity must never be performed under load in daylight conditions.

☀️ The only safe approach

fully isolate the DC input
wait for zero PV generation (night or fully de-energized system)
verify polarity with a multimeter before any disconnection
avoid disconnecting parallel strings under load at all costs

⚠️ Final takeaway

This case shows that Error 2011 is not always a simple wiring issue.

In real field conditions it may result from:

accumulated human wiring mistakes
incorrect polarity identification
lack of proper verification steps
dangerous DC string configurations

In the worst case, it can lead to arc faults and permanent damage to the inverter’s MPPT input stage.

✅ Conclusion

Huawei Error 2011 (String Reversed) indicates reversed PV polarity. The issue is typically resolved by checking DC wiring, correcting MC4 connections, and verifying proper string configuration.

⚡ Suggested FAQ

Q: What does Huawei Error 2011 mean?
A: It means the PV string polarity is reversed or incorrectly connected.

Q: Is Error 2011 dangerous?
A: It can be dangerous if combined with parallel string miswiring, potentially leading to DC arc faults.

Q: How do you fix Error 2011?
A: Correct DC polarity, check MC4 connectors, and verify string configuration.